On my 7 port hub I have:
- FitBit charger
- 30-pin dock cable
- Lightning cable
- Printer
- Blu-ray drive (takes 2 ports for the extra power)
- Multi-card reader
That's it, all 7 ports used on the hub using just one on the iMac. Then on the iMac I have the wired keyboard and a USB 3.0 drive connected. That leaves me with one free USB port on the iMac for things that I rarely use like the cable to sync my Harmony remote, or the monthly clone of my HD that I connect and disconnect after it clones the disk, etc.